I have a A2 type muzzle brake that came on a upper I recently purchased.  It is the same size as the A2 flash hider that was on the Colt upper that I just sold.  The qusetion is, would this be legal on the post ban upper I intend to put this upper on?  It is threaded but has the lug shaved and the brake is going to be pinned on.  I have a 1" reverse flash hider that I was going to have converted to a muzzle brake, but I can't find anyone to do it.

If it has an outside diameter of 22 mm it's a grenade launcher and therefore an evil feature.

I'll have to check that.  Thanks